Package net.sf.saxon.value

Class AtomicValue

java.lang.Object
net.sf.saxon.value.AtomicValue
All Implemented Interfaces:
Iterable<AtomicValue>, AtomicSequence, GroundedValue, IdentityComparable, Item, Sequence, ConversionResult
Direct Known Subclasses:
Base64BinaryValue, BooleanValue, CalendarValue, DurationValue, HexBinaryValue, NumericValue, QualifiedNameValue, StringValue
public abstract class AtomicValue extends Object implements Item, AtomicSequence, ConversionResult, IdentityComparable
The AtomicValue class corresponds to the concept of an atomic value in the XPath 2.0 data model. Atomic values belong to one of the 19 primitive types defined in XML Schema; or they are of type xs:untypedAtomic; or they are "external objects", representing a Saxon extension to the XPath 2.0 type system.

The AtomicValue class contains some methods that are suitable for applications to use, and many others that are designed for internal use by Saxon itself. These have not been fully classified. At present, therefore, none of the methods on this class should be considered to be part of the public Saxon API.

The AtomicValue class and its subclasses are essentially immutable (since 12.x). There is an exception, in that DecimalValue caches the result of converting its value to a double internally.

  • Field Details

    • typeLabel

      protected final AtomicType typeLabel

  • Constructor Details

    • AtomicValue

      public AtomicValue(AtomicType typeLabel)

  • Method Details

    • atomize

      public AtomicSequence atomize() throws XPathException
      Atomize the item.
      Specified by:
      atomize in interface Item
      Returns:
      the result of atomization
      Throws:
      XPathException - if atomization is not allowed for this kind of item

    • head

      public final AtomicValue head()
      To implement Sequence, this method returns the item itself
      Specified by:
      head in interface AtomicSequence
      Specified by:
      head in interface GroundedValue
      Specified by:
      head in interface Item
      Specified by:
      head in interface Sequence
      Returns:
      this item

    • getLength

      public int getLength()
      Get the length of the sequence
      Specified by:
      getLength in interface AtomicSequence
      Specified by:
      getLength in interface GroundedValue
      Specified by:
      getLength in interface Item
      Returns:
      the number of items in the sequence (always one)

    • isUntypedAtomic

      public boolean isUntypedAtomic()
      Ask whether the value is of type xs:untypedAtomic
      Returns:
      true if the value is untyped atomic

    • getXPathMatchKey

      public abstract AtomicMatchKey getXPathMatchKey(StringCollator collator, int implicitTimezone) throws NoDynamicContextException
      Get an object value that implements the XPath equality comparison semantics for this value. A collation is supplied for comparing strings, and an implicit timezone for comparing date/time values that have no saved timezone. The returned object supports equality matching only, not ordering. An atomic value may return itself as its own AtomicMatchKey provided that its equality semantics are context-free.
      Parameters:
      collator - the collation to be used when comparing strings
      implicitTimezone - the implicit timezone in the dynamic context, used when comparing dates/times with and without timezone
      Returns:
      an Object whose equals() and hashCode() methods implement the XPath comparison semantics with respect to this atomic value. If ordered is specified, the result will either be null if no ordering is defined, or will be a Comparable
      Throws:
      NoDynamicContextException - if the supplied implicit timezone is "NO_TIMEZONE" (meaning unknown), and the implicit timezone is actually required because the value in question is a date/time value with no timezone. This can cause a failure to evaluate expressions statically (because the implicit timezone is not known statically), and it will then be caught, meaning that the expression has to be evaluated dynamically.

    • getXPathComparable

      public abstract XPathComparable getXPathComparable(StringCollator collator, int implicitTimezone) throws NoDynamicContextException
      Get an object value that implements the XPath equality and ordering comparison semantics for this value. A collation is supplied for comparing strings, and an implicit timezone for comparing date/time values that have no saved timezone. An atomic value may return itself as the result, provided that its ordering rules are independent of the collation and timezone, and provided that it implements the XPathComparable interface: which means that its compareTo, equals, and hashCode methods must be compatible with the rules for XPath value comparisons.
      Parameters:
      collator - the collation to be used when comparing strings
      implicitTimezone - the implicit timezone in the dynamic context, used when comparing dates/times with and without timezone
      Returns:
      an Object that implements the XPath value comparison semantics with respect to this atomic value. For an atomic type that is not ordered (according to XPath rules), return null.
      Throws:
      NoDynamicContextException - if the supplied implicit timezone is "NO_TIMEZONE" (meaning unknown), and the implicit timezone is actually required because the value in question is a date/time value with no timezone. This can cause a failure to evaluate expressions statically (because the implicit timezone is not known statically), and it will then be caught, meaning that the expression has to be evaluated dynamically.

    • asMapKey

      public AtomicMatchKey asMapKey()
      Get a value whose equals() method follows the "same key" rules for comparing the keys of a map.
      Returns:
      a value with the property that the equals() and hashCode() methods follow the rules for comparing keys in maps.

    • equals

      public boolean equals(Object o)
      The equals() methods on atomic values is defined to follow the semantics of eq when applied to two atomic values. When the other operand is not an atomic value, the result is undefined (may be false, may be an exception). When the other operand is an atomic value that cannot be compared with this one, the method must throw a ClassCastException.

      The hashCode() method is consistent with equals().

      Overrides:
      equals in class Object
      Parameters:
      o - the other value
      Returns:
      true (in a subclass) if the other operand is an atomic value and the two values are equal as defined by the XPath eq operator

    • hashCode

      public int hashCode()
      Returns a hash code value for the object.
      Overrides:
      hashCode in class Object

    • isIdentical

      public boolean isIdentical(AtomicValue v)
      Determine whether two atomic values are identical, as determined by XML Schema rules. This is a stronger test than equality (even schema-equality); for example two dateTime values are not identical unless they are in the same timezone.

      Note that even this check ignores the type annotation of the value. The integer 3 and the short 3 are considered identical, even though they are not fully interchangeable. "Identical" means the same point in the value space, regardless of type annotation.

      NaN is identical to itself.

      Parameters:
      v - the other value to be compared with this one
      Returns:
      true if the two values are identical, false otherwise.

    • isIdentical

      public boolean isIdentical(IdentityComparable other)
      Determine whether two IdentityComparable objects are identical. This is a stronger test than equality (even schema-equality); for example two dateTime values are not identical unless they are in the same timezone.
      Specified by:
      isIdentical in interface IdentityComparable
      Parameters:
      other - the value to be compared
      Returns:
      true if the two values are identical, false otherwise

    • identityHashCode

      public int identityHashCode()
      Get a hashCode that offers the guarantee that if A.isIdentical(B), then A.identityHashCode() == B.identityHashCode()
      Specified by:
      identityHashCode in interface IdentityComparable
      Returns:
      a hashCode suitable for use when testing for identity.

    • getUnicodeStringValue

      public UnicodeString getUnicodeStringValue()
      Get the value of the item as a UnicodeString.
      Specified by:
      getUnicodeStringValue in interface AtomicSequence
      Specified by:
      getUnicodeStringValue in interface GroundedValue
      Specified by:
      getUnicodeStringValue in interface Item
      Returns:
      the string value (the result of casting to string using the XPath casting rules)

    • getCanonicalLexicalRepresentation

      public UnicodeString getCanonicalLexicalRepresentation()
      Get the canonical lexical representation as defined in XML Schema. This is not always the same as the result of casting to a string according to the XPath rules.
      Specified by:
      getCanonicalLexicalRepresentation in interface AtomicSequence
      Returns:
      the canonical lexical representation if defined in XML Schema; otherwise, the result of casting to string according to the XPath 2.0 rules

    • itemAt

      public final AtomicValue itemAt(int n)
      Get the n'th item in the sequence (starting from 0). This is defined for all Values, but its real benefits come for a sequence Value stored extensionally (or for a MemoClosure, once all the values have been read)
      Specified by:
      itemAt in interface AtomicSequence
      Specified by:
      itemAt in interface GroundedValue
      Specified by:
      itemAt in interface Item
      Parameters:
      n - position of the required item, counting from zero.
      Returns:
      the n'th item in the sequence, where the first item in the sequence is numbered zero. If n is negative or >= the length of the sequence, returns null.

    • getItemType

      public final AtomicType getItemType()
      Determine the data type of the value
      Returns:
      the type annotation of the atomic value

    • getPrimitiveType

      public abstract BuiltInAtomicType getPrimitiveType()
      Determine the primitive type of the value. This delivers the same answer as getItemType().getPrimitiveItemType(). The primitive types are the 19 primitive types of XML Schema, plus xs:integer, xs:dayTimeDuration and xs:yearMonthDuration, and xs:untypedAtomic. For external objects, the result is xs:anyAtomicType.
      Returns:
      the primitive type

    • getUType

      public final UType getUType()
      Determine the UType of the value. This delivers the same answer as getItemType().getUType()
      Returns:
      the primitive UType

    • getCardinality

      public final int getCardinality()
      Determine the static cardinality
      Returns:
      code identifying the cardinality
      See Also:

    • copyAsSubType

      public abstract AtomicValue copyAsSubType(AtomicType typeLabel)
      Create a copy of this atomic value, with a different type label
      Parameters:
      typeLabel - the type label of the new copy. The caller is responsible for checking that the value actually conforms to this type.
      Returns:
      the copied value

    • isNaN

      public boolean isNaN()
      Test whether the value is the special value NaN
      Returns:
      true if the value is float NaN or double NaN or precisionDecimal NaN; otherwise false

    • getPrimitiveStringValue

      public abstract UnicodeString getPrimitiveStringValue()
      Convert the value to a string, using the serialization rules for the primitive type. This is the result of conversion to a string except that postprocessing defined by the saxon:preprocess facet is not (yet) applied.
      Returns:
      the value converted to a string according to the rules for the primitive type

    • effectiveBooleanValue

      public boolean effectiveBooleanValue() throws XPathException
      Get the effective boolean value of the value
      Specified by:
      effectiveBooleanValue in interface GroundedValue
      Returns:
      true, unless the value is boolean false, numeric zero, or zero-length string
      Throws:
      XPathException - if effective boolean value is not defined for this type (the default behaviour)

    • getComponent

      public AtomicValue getComponent(AccessorFn.Component component) throws XPathException
      Method to extract components of a value. Implemented by some subclasses, but defined at this level for convenience
      Parameters:
      component - identifies the required component, as a constant defined in class AccessorFn
      Returns:
      the value of the requested component of this value
      Throws:
      XPathException - if a dynamic error occurs
      UnsupportedOperationException - if applied to a value of a type that has no components

    • checkPermittedContents

      public void checkPermittedContents(SchemaType parentType, StaticContext env, boolean whole) throws XPathException
      Check statically that the results of the expression are capable of constructing the content of a given schema type.
      Parameters:
      parentType - The schema type
      env - the static context
      whole - true if this atomic value accounts for the entire content of the containing node
      Throws:
      XPathException - if the expression doesn't match the required content type

    • checkValidInJavascript

      public void checkValidInJavascript() throws XPathException
      Check that the value can be handled in SaxonJS
      Throws:
      XPathException - if it can't be handled in SaxonJS

    • asAtomic

      public AtomicValue asAtomic()
      Calling this method on a ConversionResult returns the AtomicValue that results from the conversion if the conversion was successful, and throws a ValidationException explaining the conversion error otherwise.

      Use this method if you are calling a conversion method that returns a ConversionResult, and if you want to throw an exception if the conversion fails.

      Specified by:
      asAtomic in interface ConversionResult
      Returns:
      the atomic value that results from the conversion if the conversion was successful

    • toString

      public String toString()
      Get string value.
      Overrides:
      toString in class Object

    • toShortString

      public String toShortString()
      Description copied from interface: Item
      Provide a short string showing the contents of the item, suitable for use in error messages
      Specified by:
      toShortString in interface GroundedValue
      Specified by:
      toShortString in interface Item
      Returns:
      a depiction of the item suitable for use in error messages

    • show

      public String show()
      Display the value for diagnostics. In general show() for an atomic value displays the value as it would be written in XPath: that is, as a literal if available, or as a call on a constructor function otherwise.
      Returns:
      a string representation of this value

    • iterate

      public SingleAtomicIterator iterate()
      Get an iterator over all the items in the sequence
      Specified by:
      iterate in interface AtomicSequence
      Specified by:
      iterate in interface GroundedValue
      Specified by:
      iterate in interface Item
      Specified by:
      iterate in interface Sequence
      Returns:
      an iterator over all the items

    • iterator

      public Iterator<AtomicValue> iterator()
      Returns a Java iterator over the atomic sequence.
      Specified by:
      iterator in interface Iterable<AtomicValue>
      Returns:
      an Iterator.

    • getGenre

      public final Genre getGenre()
      Get the genre of this item
      Specified by:
      getGenre in interface Item
      Returns:
      the genre: specifically, Genre.ATOMIC;